I’m not sure that doing something that only directly benefits other people but makes you feel better about yourself as you’ve done something good (or less bad as you’ve not spent the money on something you’d have felt guilty about) isn’t in your self-interest. Other kinds of making yourself feel good count.

When people use the phrase rational self interest they’re overwhelmingly meaning what Ayn Rand called rational self interest. If you take the words literally, they apply to any political philosophy as no one’s trying to design a system against their own interests. The disagreements come from people disagreeing what their interests are and how they can feasibly have them fulfilled, not because they don’t want their interests fulfilled. No one else bothers using the phrase because it’s obviously the goal and stating that would be entirely redundant, but risk making it sound like you were advocating for something Randian.

All of Ayn Rand’s own examples of rational self interest were irrational and against her interests. It’s such an easy philosophy to mock because it’s just really stupid. True rational self interest would involve creating cooperative structures that give a safety net if anything goes wrong just like how it’s rational to get home insurance even if you don’t expect to burn your house down. Anyone drawing Randian conclusions can’t have thought of rational self interest.